I like Jeff's proposal. None of the solutions which have been
discussed so far to maintain syntactic compatibility is very
appealing. Surely, it is semantic compatibility that we want to
ensure: we want to be able to import RDFS specifications into OWL and
maybe we also want to output RDFS from OWL. We can do this by
ensuring that OWL is a true semantic extension of RDFS. Once
semantic compatibility is guaranteed, developers will simply have to
ensure that OWL tools are able to read in RDFS specs, which does not
seem like a major chore. The only drawback will be that a current
RDFS parser will not understand OWL. Is this really such a big deal?
People will simply develop 'semantic web' parsers which will handle
both RDFS and OWL. And as Jeff says, once we are free from the
RDFS-related constraint, then we can really create a syntax that
clearly and precisely suits our needs.
Enrico
At 11:22 am -0500 26/3/02, Jeff Heflin wrote:
>Dan,
>
>Can you describe what you don't like about my proposal? Is it the fact
>that it doesn't build on RDF Schema? If so, let me try to persuade you
>otherwise. As time has gone by with this Semantic Web stuff (I've been
>doing it for the last five years), I have begun to realize that RDF
>Schema is really the thorn in our side that makes everything difficult.
>No offense to the working group that designed it, mind you, they had a
>good solution to their problem, its just that this approach does not
>make it easy to build logical languages on top of it. The problem of
>course is the fact that your only building block is tripples. Sure, it's
>not impossible to develop ad-hoc methods of getting around this (such as
>unasserted tripples), but why bother? We can just create an XML syntax
>that clearly and precisely suits our needs. We can even reuse RDF for
>the data portion, because that is what RDF is good at.
>
>Let me try to refute the likely arguments in favor of building on top of
>RDF schema:
>
>1) RDF Schema is already a W3C standard - But it never reached
>recommendation status, indicating that people had serious reservations
>about it. However, even if it did become a standard, OWL could be an
>alternative approach for describing RDF ontologies for those who want
>more expressive power, while RDF Schema can be used by the database
>community. You could even have an OWL ontologies and RDF Schemas that
>describe the same vocabulary and automate the (partial) generation of
>one from the other.
>
>2) RDF Schema tools will have to be changed - So what. DAML+OIL tools
>will have to be changed as well if they want to talk OWL. We are too
>early in the Semantic Web process to be over-constrained by backward
>compatibility.
>
>3) But people are already using RDF - Not a problem. As I've said, I
>want to reuse RDF for the data/instance portion of the language. My
>proposal is that OWL is an alternative way to describing schemas. The
>existing RDF data could be reused by simply creating OWL versions of the
>schemas (I can't imagine that there are many of them out there, and like
>I said earlier, this can probably be automated rather easily).
>
>If someone has a good argument why we should let RDF Schema shoehorn us
>into a suboptimal solution, I'd like to hear it. If not, then the basic
>strategy of my proposal should be acceptable.
>
>Jeff
>
>Dan Connolly wrote:
>>
>> On Fri, 2002-03-22 at 14:54, Jeff Heflin wrote:
>> [...]
>> > In
>> > terms of Peter and Dieter's "Layering" document, this proposal is
>> > probably best described as a diverging sytax and diverging semantics
>> > proposal (although it might be a syntactic and semantic extension of
>> > RDF).
>>
>> I'm not sure I really like this, but I know I prefer
>> it to the same-syntax-different-semantics approaches.
>>
>> i.e. in this approach, if you mean something
>> different, you say it a different way.
>>
>> I would find it completely unacceptable if
>> two different W3C recommendations gave
>> different meanings to the same document.
> >
>> --
>> Dan Connolly, W3C http://www.w3.org/People/Connolly/